Integrated Circuit Package Pad and Methods of Forming

ABSTRACT

A semiconductor device and method for forming the semiconductor device is provided. The semiconductor device includes an integrated circuit having through vias adjacent to the integrated circuit die, wherein a molding compound is interposed between the integrated circuit die and the through vias. The through vias have a projection extending through a patterned layer, and the through vias may be offset from a surface of the patterned layer. The recess may be formed by selectively removing a seed layer used to form the through vias.

This application is a divisional of U.S. application Ser. No.14/743,451, filed on Jun. 18, 2015, entitled “Integrated Circuit PackagePad and Methods of Forming,” which claims the benefit of U.S.Provisional Application No. 62/087,090, filed on Dec. 3, 2014, entitled“Integrated Circuit Package Pad and Methods of Forming Same,” eachapplication is hereby incorporated herein by reference.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment. Semiconductor devices are typically fabricated bysequentially depositing insulating or dielectric layers, conductivelayers, and semiconductive layers of material over a semiconductorsubstrate, and patterning the various material layers using lithographyto form circuit components and elements thereon. Dozens or hundreds ofintegrated circuits are typically manufactured on a single semiconductorwafer. The individual dies are singulated by sawing the integratedcircuits along scribe lines. The individual dies are then packagedseparately, in multi-chip modules, or in other types of packaging.

The semiconductor industry has experienced rapid growth due tocontinuous improvement in the integration density of a variety ofelectronic components (e.g., transistors, diodes, resistors, capacitors,etc.). For the most part, this improvement in integration density hascome from repeated reductions in minimum feature size (e.g., shrinkingthe semiconductor process node towards the sub-20 nm node), which allowsmore components to be integrated into a given area. As the demand forminiaturization, higher speed, and greater bandwidth, as well as lowerpower consumption and latency has grown recently, there has grown a needfor smaller and more creative packaging techniques for semiconductordies.

As semiconductor technologies further advance, stacked semiconductordevices, e.g., three dimensional integrated circuits (3DICs), haveemerged as an effective alternative to further reduce the physical sizeof semiconductor devices. In a stacked semiconductor device, activecircuits such as logic, memory, processor circuits, and the like arefabricated on different semiconductor wafers. Two or more semiconductorwafers may be installed or stacked on top of one another to furtherreduce the form factor of the semiconductor device. Package-on-package(POP) devices are one type of 3DIC wherein dies are packaged and arethen packaged together with another packaged die or dies.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1-9 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

FIGS. 10-12 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

FIGS. 13-20 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

FIGS. 21-23 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

FIGS. 24-31 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

FIGS. 32-40 are cross-sectional views of various intermediate steps offorming semiconductor device in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments will be described with respect to embodiments in a specificcontext, namely a three dimensional (3D) integrated fan-out (InFO)package-on-package (PoP) device. Other embodiments may also be applied,however, to other electrically connected components, including, but notlimited to, package-on-package assemblies, die-to-die assemblies,wafer-to-wafer assemblies, die-to-substrate assemblies, in assemblingpackaging, in processing substrates, interposers, substrates, or thelike, or mounting input components, boards, dies or other components, orfor connection packaging or mounting combinations of any type ofintegrated circuit or electrical component.

FIGS. 1-9 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some embodiments.Referring first to FIG. 1, there is shown a carrier substrate 100 havinga release layer 102 and a backside dielectric layer 104 formed thereon.Generally, the carrier substrate 100 provides temporary mechanical andstructural support during subsequent processing steps. The carriersubstrate 102 may include any suitable material, such as, for example,silicon based materials, such as a silicon wafer, glass or siliconoxide, or other materials, such as aluminum oxide, a ceramic material,combinations of any of these materials, or the like. In someembodiments, the carrier substrate 100 is planar in order to accommodatefurther processing.

The release layer 102 is an optional layer formed over the carriersubstrate 100 that may allow easier removal of the carrier substrate100. As explained in greater detail below, various layers and deviceswill be placed over the carrier substrate 100, after which the carriersubstrate 100 may be removed. The optional release layer 102 aids in theremoval of the carrier substrate 100, reducing damage to the structuresformed over the carrier substrate 100. The release layer 102 may beformed of a polymer-based material. In some embodiments, the releaselayer 102 is an epoxy-based thermal release material, which loses itsadhesive property when heated, such as a Light-to-Heat-Conversion (LTHC)release coating. In other embodiments, the release layer 102 may be anultra-violet (UV) glue, which loses its adhesive property when exposedto UV light. The release layer 102 may be dispensed as a liquid andcured. In other embodiments, the release layer 102 may be a laminatefilm laminated onto the carrier substrate 102. Other release layers maybe utilized.

The backside dielectric layer 104 may be a polymer (such aspolybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), or the like),a nitride (such as silicon nitride or the like), an oxide (such assilicon oxide, PhosphoSilicate Glass (PSG), BoroSilicate Glass (BSG),Boron-doped PhosphoSilicate Glass (BPSG), or a combination thereof, orthe like), or the like, and may be formed, for example, by spin coating,lamination, Chemical Vapor Deposition (CVD), or the like. In someembodiments, the backside dielectric layer 104 has a thickness of about1 μm to about 10 μm, such as about 7 μm.

Referring now to FIG. 2, there is shown formation of conductivestructures 205 in accordance with some embodiments. The conductivestructures 205 provide an electrical connection from one side of thepackage to another side of the package. For example, as will beexplained in greater detail below, a die will be mounted to the backsidedielectric layer 104 and a molding compound will be formed around theconductive structures and the die, thereby forming through vias.Subsequently, another device, such as another die, package, substrate,or the like, may be attached to the die and the molding compound. Theconductive structures 205 provide an electrical connection between theanother device and the backside of the package without having to passelectrical signals through the die mounted to the backside dielectriclayer 104.

The conductive structures 205, for example, by forming a conductive seedlayer (not shown) over the backside dielectric layer 104. In someembodiments, the seed layer is a metal layer, which may be a singlelayer or a composite layer comprising a plurality of sub-layers formedof different materials. The seed layer may be made of copper, titanium,nickel, gold, or a combination thereof, or the like. In someembodiments, the seed layer comprises a titanium layer and a copperlayer over the titanium layer. The seed layer may be formed using, forexample, physical vapor deposition (PVD), CVD, atomic layer deposition(ALD), a combination thereof, or the like. The seed layer may compriseone or more layers.

A mask, such as a patterned photoresist layer, may be deposited andpatterned to define the shape of the conductive structures 205, whereinopenings in the mask expose the seed layer. The openings may be filledwith a conductive material using, for example, an electroless platingprocess or an electrochemical plating process. The plating process mayuni-directionally fill openings (e.g., from seed layer upwards) in thepatterned photoresist. Uni-directional filling may allow for moreuniform filling of such openings, particularly for high aspect ratiothrough vias. Alternatively, a seed layer may be formed on sidewalls ofopenings in the patterned photoresist, and such openings may be filledmulti-directionally. Subsequently, the photoresist may be removed in anashing and/or wet strip process, and excess materials of the seed layermay be etched, leaving the conductive structures 205 over the backsidedielectric layer 104 as illustrated in FIG. 2. The conductive structures205 can also be realized with metal wire studs placed by a wire bondingprocess, such as a copper wire bonding process. The use of a wirebonding process may eliminate the need for depositing a seed layer,depositing and patterning a photoresist, and plating to form theconductive structures 205.

FIG. 3 illustrates attaching an integrated circuit die 310 to thebackside dielectric layer 104 in accordance with some embodiments. Insome embodiments, the integrated circuit die 310 may be adhered to thebackside dielectric layer 104 by an adhesive 312, such as a die-attachfilm (DAF). A thickness of the adhesive 312 may be in a range from about10 μm to about 30 μm. The integrated circuit die 310 may be a single dieas illustrated in FIG. 3, or in some embodiments, two or more than twodies may be attached, and may include any die suitable for a particularapproach. For example, the integrated circuit die 310 may include astatic random access memory (SRAM) chip or a dynamic random accessmemory (DRAM) chip, a processor, a memory chip, logic chip, analog chip,digital chip, a central processing unit (CPU), a graphics processingunit (GPU), or a combination thereof, or the like. The integratedcircuit die 310 may be attached to a suitable location for a particulardesign or application. For example, FIG. 3 illustrates an embodiment inwhich the integrated circuit die 310 is mounted in a center regionwherein the conductive structures 205 are positioned around a perimeter.In other embodiments, the integrated circuit die 310 may be offset froma center. Before being attached to the backside dielectric layer 104,the integrated circuit die 310 may be processed according to applicablemanufacturing processes to form integrated circuits in the integratedcircuit die 310.

In some embodiments, the integrated circuit die 310 is mounted to thebackside dielectric layer 104 such that die contacts 314 are facing awayfrom or distal to the backside dielectric layer 104. The die contacts314 provide an electrical connection to the electrical circuitry formedon the integrated circuit die 310. The die contacts 314 may be formed onan active side of the integrated circuit die 310, or may be formed on abackside and comprise through vias. The die contacts 314 may furthercomprise through vias providing an electrical connection between a firstside and a second side of the integrated circuit die 310. In anembodiment, the conductive material of the die contacts 314 is copper,tungsten, aluminum, silver, gold, tin, a combination thereof, or thelike.

FIG. 4 illustrates encapsulating the integrated circuit die 310 and theconductive structures 205 by an encapsulant 416, thereby forming throughvias 206, in accordance with some embodiments. In some embodiments, theencapsulating process is a wafer-level molding process. For example,encapsulant 416 is dispensed to fill gaps between the integrated circuitdie 310 and the through vias 206. The encapsulant 416 may include anysuitable material such as a molding compound, an epoxy resin, a polymer,a molding underfill, or the like. Suitable methods for forming theencapsulant 416 may include compressive molding, transfer molding,liquid encapsulant molding, or the like. For example, the encapsulant416 may be dispensed between the integrated circuit die 310 and theconductive structures 205 in liquid form. Subsequently, a curing processis performed to solidify the encapsulant 416.

In some embodiments, the encapsulant 416 is formed to cover the throughvias 206 and/or the die contacts 314. In these embodiments, a mechanicalgrinding, chemical mechanical polish (CMP), or other etch back techniquemay be employed to remove excess portions of the encapsulant 416 andexpose the die contacts 314 of the integrated circuit die 310. Afterplanarization, top surfaces of the encapsulant 416, the integratedcircuit die 310, and the through vias 206 may be substantially level.

FIG. 5 illustrates formation of a front-side redistribution structure518 in accordance with some embodiments. Generally, the front-sideredistribution structure 518 comprises one or more redistribution layers(RDLs) and provides a conductive pattern to be formed to allow a pin-outcontact pattern for a completed package different than the pattern ofthe through vias 206 and the die contacts 314, allowing for greaterflexibility in the placement of the through vias 206 and the integratedcircuit die 310. The RDLs may be utilized to provide an externalelectrical connection to the integrated circuit die 310 and/or to thethrough vias 206. The RDLs may further be used to electrically couplethe integrated circuit die 310 to the through vias 206, which may beelectrically coupled to one or more other packages, package substrates,components, the like, or a combination thereof. The numbers ofillustrated metallization layers in the front-side redistributionstructure 518 are only for illustrative purposes and are not limiting.The front-side redistribution structure 518 may comprise any number ofdielectric layers, metallization patterns, and vias. For example, FIG. 5illustrates an embodiment in which the redistribution structure 518includes three dielectric layers 520 a, 520 b, and 520 c, collectivelyreferred to as the front-side dielectric layers 520, with respectivemetallization patterns and vias, as will be discussed below, althoughother embodiments may have fewer or more.

The first dielectric layer 520 a is formed on the encapsulant 416 andintegrated circuit die 310. In some embodiments, the first dielectriclayer 520 a is formed of a polymer, which may be a photo-sensitivematerial such as polybenzoxazole (PBO), polyimide, benzocyclobutene(BCB), or the like, that may be patterned using lithography. In otherembodiments, the first dielectric layer 520 a is formed of a nitridesuch as silicon nitride, an oxide such as silicon oxide, PhosphoSilicateGlass (PSG), BoroSilicate Glass (BSG), Boron-doped PhosphoSilicate Glass(BPSG), or the like. The first dielectric layer 520 a may be formed byspin coating, lamination, CVD, the like, or a combination thereof. Thefirst dielectric layer 520 a is then patterned to form openings toexpose portions of the die contacts 314 and the through vias 206. Inembodiments in which the first dielectric layer 520 a is formed of aphoto-sensitive material, the patterning may be performed by exposingthe first dielectric layer 520 a in accordance with a desired patternand developed to remove the unwanted material, thereby exposing portionsof the die contacts 314 and the through vias 206. Other methods, such asusing a patterned mask and etching, may also be used to pattern thefirst dielectric layer 520 a.

A first metallization pattern 522 a is formed on the first dielectriclayer 520 a and is in electrical contact with the exposed die contacts314 and through vias 206. As an example to form first metallizationpattern 522 a, a seed layer (not shown) is formed over the firstdielectric layer 522 a and in the openings formed in the firstdielectric layer 522 a. In some embodiments, the seed layer is a metallayer, which may be a single layer or a composite layer comprising aplurality of sub-layers formed of different materials. In someembodiments, the seed layer comprises a titanium layer and a copperlayer over the titanium layer. The seed layer may be formed using, forexample, PVD, or the like. A mask is then formed and patterned on theseed layer in accordance with a desired redistribution pattern. In someembodiments, the mask is a photoresist formed by spin coating or thelike and exposed to light for patterning. The pattern of the maskcorresponds to the first metallization pattern 522 a. The patterningforms openings through the mask to expose the seed layer. A conductivematerial is formed in the openings of the mask and on the exposedportions of the seed layer. The conductive material may be formed byplating, such as electroplating or electroless plating, or the like. Theconductive material may comprise a metal, like copper, titanium,tungsten, aluminum, or the like. Then, the photoresist and portions ofthe seed layer on which the conductive material is not formed, areremoved. The photoresist may be removed by an acceptable ashing orstripping process, such as using an oxygen plasma or the like. Once thephotoresist is removed, exposed portions of the seed layer are removed,such as by using an acceptable etching process, such as by wet or dryetching. The remaining portions of the seed layer and conductivematerial form the first metallization pattern 522 a. The seconddielectric layer 520 b is formed over the first dielectric layer 522 ato provide a more planar surface for subsequent layers and may be formedusing similar materials and processes as used to form the firstdielectric layer 520 a. In some embodiments, the second dielectric layer520 b is formed of polymer, a nitride, an oxide, or the like. In someembodiments, the second dielectric layer 520 b is PBO formed by aspin-on process.

A third dielectric layer 522 c and a second metallization pattern 522 bis formed on the second dielectric layer 520 b and first metallizationpattern 522 a. The third dielectric layer 522 c and the secondmetallization pattern 522 b can be formed using similar processes withsimilar materials as used for forming the first dielectric layer 520 aand the first metallization pattern 522 a as discussed above. Theopenings in the front-side dielectric layers 520 form vias thatinterconnect adjacent metallization layers, such as interconnecting thefirst metallization pattern 522 a and the through vias 206/die contacts314, and interconnecting the first metallization pattern 522 a and thesecond metallization patter 522 b.

FIG. 5 further illustrates a passivation layer 524 formed over anuppermost metallization pattern in accordance with some embodiments. Thepassivation layer 524 may be formed of a polymer, which may be aphoto-sensitive material such as PBO, polyimide, BCB, or the like, thatmay be patterned using a lithography mask. In other embodiments, thepassivation layer 524 is formed of a nitride or an oxide such as siliconnitride, silicon oxide, PSG, BSG, BPSG, or the like. The passivationlayer 524 may be formed by spin coating, lamination, CVD, the like, or acombination thereof. The passivation layer 524 is then patterned toexpose portions of the underlying metallization layer, e.g., the secondmetallization pattern 522 b. The patterning may be by an acceptableprocess, such as by exposing the passivation layer 524 to light when thedielectric layer is a photo-sensitive material or by etching using, forexample, an anisotropic etch. A single passivation layer 524 is shownfor illustrative purposes, and in other embodiments, a plurality ofpassivation layers may be used.

FIG. 5 also illustrates an under bump metallization (UBM) 526 formed andpatterned over and through the passivation layer 524, thereby forming anelectrical connection with an uppermost metallization layer, e.g., thesecond metallization layer 522 b in the embodiment illustrated in FIG.5. The under bump metallization 526 provides an electrical connectionupon which an electrical connector, e.g., a solder ball/bump, aconductive pillar, or the like, may be placed. In an embodiment, theunder bump metallization 526 includes a diffusion barrier layer, a seedlayer, or a combination thereof. The diffusion barrier layer may includeTi, TiN, Ta, TaN, or combinations thereof. The seed layer may includecopper or copper alloys. However, other metals, such as nickel,palladium, silver, gold, aluminum, combinations thereof, andmulti-layers thereof, may also be included. In an embodiment, under bumpmetallization 526 is formed using sputtering. In other embodiments,electro plating may be used.

Connectors 528 are formed over the under bump metallization 526 inaccordance with some embodiments. The connectors 528 may be solderballs, metal pillars, controlled collapse chip connection (C4) bumps,micro bumps, electroless nickel-electroless palladium-immersion goldtechnique (ENEPIG) formed bumps, combination thereof (e.g., a metalpillar having a solder ball attached thereof), or the like. Theconnectors 528 may include a conductive material such as solder, copper,aluminum, gold, nickel, silver, palladium, tin, the like, or acombination thereof. In some embodiments, the connectors 528 comprise aeutectic material and may comprise a solder bump or a solder ball, asexamples. The solder material may be, for example, lead-based andlead-free solders, such as Pb—Sn compositions for lead-based solder;lead-free solders including InSb; tin, silver, and copper (SAC)compositions; and other eutectic materials that have a common meltingpoint and form conductive solder connections in electrical applications.For lead-free solder, SAC solders of varying compositions may be used,such as SAC 105 (Sn 98.5%, Ag 1.0%, Cu 0.5%), SAC 305, and SAC 405, asexamples. Lead-free connectors such as solder balls may be formed fromSnCu compounds as well, without the use of silver (Ag). Alternatively,lead-free solder connectors may include tin and silver, Sn—Ag, withoutthe use of copper. The connectors 528 may form a grid, such as a ballgrid array (BGA). In some embodiments, a reflow process may beperformed, giving the connectors 528 a shape of a partial sphere in someembodiments. Alternatively, the connectors 528 may comprise othershapes. The connectors 528 may also comprise non-spherical conductiveconnectors, for example.

In some embodiments, the connectors 528 comprise metal pillars (such asa copper pillar) formed by a sputtering, printing, electro plating,electroless plating, CVD, or the like, with or without a solder materialthereon. The metal pillars may be solder free and have substantiallyvertical sidewalls or tapered sidewalls.

The front-side redistribution structure 518 is simplified for purposesof illustration. For example, for purposes of illustration, conductivelines have been illustrated extending only from the through vias 206,although the front-side redistribution structure 518 may be used toprovide an external electrical connection to any of the through vias 206and the die contacts 314, as well as coupling respective ones of thethrough vias 206 to respective ones of the die contacts 314.

FIG. 6 illustrates removing the carrier substrate 100 and the releaselayer 102 (see FIG. 5) to expose the backside dielectric layer 104 inaccordance with some embodiments. In some embodiments, the de-bondingincludes projecting a light such as a laser light or an UV light on therelease layer 102 so that the release layer 102 decomposes under theheat of the light and the carrier substrate 100 can be removed. Inanother embodiment, a thermal process, a chemical strip process, laserremoval, a UV treatment, the like, or a combination thereof may be used.

After separating the carrier substrate 100, a cleaning process may beused to remove the residue of the release layer 102. In embodiments inwhich an LTHC film is used as the release layer 102, a plasma cleanprocess may be used to remove the LTHC residue. For example, in someembodiments a plasma cleaning process using Ar, N₂, CF₄, O₂, or the likeas process gases. After the de-bonding of the carrier substrate 100 andthe release layer 102, the backside dielectric layer 104 is exposed.

In some embodiments, additional support may be desired. In thesesituations, a second carrier substrate (not shown) may be attached tothe passivation layer 524 and/or the connectors 528 prior to removingthe carrier substrate 100. The second carrier substrate may be attachedusing, for example, an adhesive, such as a UV adhesive.

FIG. 7 illustrates removing the backside dielectric layer 104 inaccordance with some embodiments. Generally, if electrical contact is tobe made to the through vias 206 and/or the integrated circuit die 310(such as the case in which the integrated circuit die orientation isreversed or the integrated circuit die includes through vias), then atleast a portion of the backside dielectric layer 104 is removed. It hasbeen found that laser drilling openings through the backside dielectriclayer 104 may damage the through vias as well as include many additionalprocess steps. In accordance with some embodiments disclosed herein, alaser drilling process is not necessary to expose the through vias 206,thereby reducing and/or preventing unnecessary damage.

In some embodiments, the backside dielectric layer 104 is removed usinga dry etch process using, for example, Ar, N₂, CF₄, O₂, or the like.

FIG. 8 illustrates formation of backside connectors 830 in accordancewith some embodiments. After removal of the backside dielectric layer104, backside connectors 830 may be formed directly on the through vias206. The backside connectors 830 may be formed using similar processesand materials as the front-side connectors 528.

FIG. 9 illustrates attachment of the structure illustrated in FIG. 8 toa first substrate 932 and a second substrate 934 in accordance with someembodiments. Each of the first substrate 932 and the second substrate934 may be any substrate, such as an integrated circuit die, a package,a printed circuit board, an interposer, or the like. For example, FIG. 9illustrates an embodiment in which the first substrate 932 comprises aprinted circuit board or interposer, and the second substrate 934comprises another package.

FIG. 9 also illustrates a molding underfill 936 interposed between thesecond substrate 934 and the molding encapsulant 416 according to someembodiments. In some embodiments, the molding underfill is, for example,a polymer, epoxy, and/or the like. The molding underfill protects thebackside connectors 830 from the external environment and may provideadditional support. In some embodiments, the molding underfill 936 mayextend along sidewalls of the second substrates 934 as shown in FIG. 9.In some embodiments, the molding underfill 936 may not extend alongsidewalls of the second substrate 934. Though not shown, a moldingunderfill may also be formed between the first substrate 932 andpassivation layer 524, surrounding the front-side connectors.

The figures provided herein have been simplified for purposes ofillustration and other processes may be performed. For example, thestructures shown in the figures may represent a single 3DIC package areaof a larger wafer-like structure. In some embodiments, the carriersubstrate 100 may be a wafer and the integrated circuit die may be oneof many die areas formed on the wafer. The second substrate 934 may beone of many attached to the individual die areas and the moldingunderfill 936 may be formed over the die areas. Thereafter, asingulation process may be performed to separate the individual dieareas into separate 3DIC structures such as that illustrated in FIG. 9.

FIGS. 10-12 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some additionalembodiments. Many of the structures illustrated in FIGS. 10-12 may beformed using similar processes and materials as discussed above withreference to FIGS. 1-9, wherein like reference numerals refer to likeelements, and accordingly, the description of those elements will not berepeated herein. The embodiments illustrated in FIGS. 10-12 assume theprocesses discussed above with reference to FIGS. 1-6 have beenperformed. Accordingly, the method disclosed herein include theprocesses illustrates in FIGS. 1-6 followed by the processes illustratedin FIGS. 10-12.

Referring now to FIG. 10, the backside dielectric layer 104 (see FIG. 6)is removed and the encapsulant 416 is recessed in accordance with someembodiments. As discussed above with reference to FIG. 7, the backsidedielectric layer 104 was removed such that the encapsulant 416 was notrecessed. FIG. 10 illustrates embodiments in which the encapsulant 416is recessed, thereby causing the through vias 206 to protrude through orextend above the surface of the encapsulant 416 such that a portion ofthe sidewalls of the through vias 206 are exposed.

In some embodiments, the backside dielectric layer 104 is removed andthe encapsulant 416 is recessed using, for example, an over etchprocess. For example, in some embodiments, the backside dielectric layer104 is removed in a similar manner as discussed above with reference toFIG. 7 with a longer etch time. The etch process is selective in thatlittle or no etching occurs to the through vias 206, while the longeretch time allows the etch process to continue to etch and recess theencapsulant 416.

In some embodiments, the encapsulant 416 is recessed by depth D1 ofequal to or greater than 2 μm. By recessing the encapsulant 416 andexposing sidewalls of the through vias 206 by a distance such as this,backside connectors 830 (e.g., solder) subsequently formed over thethrough vias 206 may extend along the sidewalls of the through vias 206,increasing the contact surface area. In some embodiments, this increasedcontact surface between the solder and the through vias 206 may increasethe reliability.

Referring now to FIG. 11, there is illustrated formation of backsideconnectors 830 in accordance with some embodiments. The backsideconnectors may be formed using similar processes and materials as thefront-side connectors 528 as discussed above with reference to FIG. 5.

FIG. 12 illustrates attachment of the structure illustrated in FIG. 11to a first substrate 932 and a second substrate 934 in accordance withsome embodiments. Each of the first substrate 932 and the secondsubstrate 934 may be any substrate, such as an integrated circuit die, apackage, a printed circuit board, an interposer, or the like. Forexample, FIG. 12 illustrates an embodiment in which the first substrate932 comprises a printed circuit board or interposer, and the secondsubstrate 934 comprises another package.

FIG. 12 also illustrates a molding underfill 936 interposed between thesecond substrate 934 and the molding encapsulant 416 according to someembodiments. In some embodiments, the molding underfill 936 is, forexample, a polymer, epoxy, and/or the like. The molding underfill 936protects the backside connectors 830 from the external environment andmay provide additional support. In some embodiments, the moldingunderfill 936 may extend along sidewalls of the second substrate 934 asshown in FIG. 12. In some embodiments, the molding underfill 936 may notextend along sidewalls of the second substrate 934. Though not shown, amolding underfill may also be formed between the first substrate 932 andpassivation layer 524, surrounding the front-side connectors.

The recessing of the encapsulant 416 by over etching may also roughen asurface of the encapsulant 416. The roughened surface of the encapsulant416 may increase the bonding between the encapsulant and the moldingunderfill 936, thereby reducing or preventing delamination issues.

FIGS. 13-20 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some additionalembodiments. Many of the structures illustrated in FIGS. 13-20 may beformed using similar processes and materials as discussed above withreference to FIGS. 1-12, wherein like reference numerals refer to likeelements, and accordingly, the description of those elements will not berepeated herein.

Referring first to FIG. 13, there is shown the carrier substrate 100having the release layer 102 and the backside dielectric layer 104formed thereon. The carrier substrate 100, the release layer 102, andthe backside dielectric layer 104 may be formed of similar materialsusing similar processes as described above with reference to FIG. 1. Asillustrated in FIG. 13, the backside dielectric layer 104 has beenpatterned to form openings 1340 therein. Whereas the embodimentdiscussed above with reference to FIGS. 1-2 utilized a through viahaving a relatively flat surface, as discussed below in greater detail,the openings 1340 will be utilized to form through vias having one ormore projections extending from an end of the through vias.

In embodiments in which the backside dielectric layer 104 is formed of aphotosensitive material, such as PBO, the backside dielectric layer 104may be patterned by exposing the backside dielectric layer 104 inaccordance with a desired pattern of the projections and developing thebackside dielectric layer 104 to remove portions of the backsidedielectric layer 104 corresponding to the locations of the projections.In some embodiments, the backside dielectric layer 104 has a thicknessof about 1 μm to about 10 μm, such as about 7 μm. As will be discussedin greater detail below, a through via will subsequently be formed overthe backside dielectric layer 104, wherein the openings 1340 correspondto through via projections. A thickness of about 7 μm provides asufficient thickness to shape the through via projections (e.g., taperedsidewalls) as well as providing a sufficient process window for an overetch process to expose portions of the sidewalls of the through viaprojections.

FIGS. 14-18 illustrate subsequent processes similar to those discussedabove with reference to FIGS. 2-6, respectively. As illustrated in FIG.14, the conductive structures 205 include conductive structureprojections 1441, corresponding to the openings 1340 illustrated in FIG.13. The conductive structures 205 and the conductive structureprojections 1441 may be formed using similar processes and materialsdiscussed above. For example, the seed layer (not shown) may be formedover the backside dielectric layer 104 and along sidewalls and a bottomof the openings 1340. A patterned mask (not shown) may be formed overthe seed layer, wherein the patterned mask has openings corresponding tothe locations of the conductive structures 205. A conductive material isformed in the openings, the patterned mask is removed, and excessmaterial of the seed layer is removed, forming the conductive structures205 having the conductive structure projections 1441 as illustrated inFIG. 14.

FIG. 18 illustrates the structure after performing the processesdiscussed above with reference to FIGS. 2-6, including the removal ofthe carrier substrate 100 and the release layer 102. As illustrated inFIG. 16, an encapsulant 416 is formed adjacent the conductive structures205, thereby forming through vias 206 and through via projections 1442.In some embodiments, the backside dielectric layer 104 remains such thata surface of the backside dielectric layer 104 is relatively planar withthe through via projections 1442, allowing for process variations offorming the through vias 206 and the backside dielectric layer 104 onthe same release layer 102.

Thereafter, as illustrated in FIGS. 19 and 20, processes similar tothose discussed above with reference to FIGS. 8 and 9, respectively, maybe performed to form the backside connectors 830, attach the structureto other substrates (e.g., the first substrate 932 and/or the secondsubstrate 934), and forming a molding underfill 936. As illustrated inFIG. 20, the backside connectors 830 connect directly to the through viaprojections 1442 in some embodiments. In some embodiments, the backsideconnectors 830 may be provided on the second substrate 934 and thenattached to the through via projections 1442.

FIGS. 21-23 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some embodiments.FIGS. 21-23 assume the processes discussed above with reference to FIGS.13-18 have been previously performed, wherein like reference numeralsrefer to like elements. Referring first to FIG. 21, there is shown thestructure of FIG. 18 after performing a recess process to recess thebackside dielectric layer 104 to expose at least portions of thesidewalls of the through via projections 1442. The recess process may beperformed using a dry etch process using, for example, Ar, N₂, CF₄, O₂,or the like. The recess process may result in exposing sidewalls of thethrough via projections 1442 increasing the wetting surface for thesubsequently formed backside connectors 830. In some embodiments, thebackside dielectric layer 104 is recessed such that the through viaprojections 1442 protrude for a distance D1 greater than about 2 μm.

By recessing the backside dielectric layer 104 and exposing sidewalls ofthe through vias projections 1442 by a distance such as D1, backsideconnectors 830 (e.g., solder) subsequently formed over the through viasprojections 1442 may extend along the sidewalls of the through viasprojections 1442 and/or the through vias 206, increasing the contactsurface area. In some embodiments, this increased contact surfacebetween the solder and the through vias projections 1442 and/or thethrough vias 206 may increase the reliability.

Thereafter, as illustrated in FIGS. 22 and 23, processes similar tothose discussed above with reference to FIGS. 19 and 20, respectively,may be performed to form the backside connectors 830, attach thestructure to other substrates (e.g., the first substrate 932 and/or thesecond substrate 934), and forming a molding underfill 936. In someembodiments, the molding underfill 936 may not extend along sidewalls ofthe second substrate 934. As illustrated in FIG. 22, the backsideconnectors 830 sit directly on the through via projections 1442 in someembodiments. Though not shown, a molding underfill may also be formedbetween the first substrate 932 and passivation layer 524, surroundingthe front-side connectors.

FIGS. 24-29 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some embodiments. Aswill be explained in greater detail below, a sacrificial layer will beused to aid in the process of forming through vias having one or morethrough via projections, similar to the structure discussed above withreference to FIGS. 21-23. Referring first to FIG. 24, similar processesand similar materials are used to form a structure similar to thatdiscussed above with reference to FIG. 13 having an additional featureof a sacrificial backside dielectric layer 2450 being formed over therelease layer 102 prior to forming the backside dielectric layer 104,wherein like reference numerals refer to like elements.

In some embodiments, the sacrificial backside dielectric layer 2450 maybe a polymer (such as polybenzoxazole (PBO), polyimide, benzocyclobutene(BCB), or the like), a nitride (such as silicon nitride or the like), anoxide (such as silicon oxide, PhosphoSilicate Glass (PSG), BoroSilicateGlass (BSG), Boron-doped PhosphoSilicate Glass (BPSG), or a combinationthereof, or the like), or the like, and may be formed, for example, byspin coating, lamination, Chemical Vapor Deposition (CVD), or the like.In some embodiments, the sacrificial backside dielectric layer 2450 is aphotoresist material (e.g., PBO) that has been coated on the surface anddeveloped. In some embodiments, the sacrificial layer 2450 has athickness of about 2 μm.

Thereafter, the backside dielectric layer 104 is formed and patternedover the sacrificial backside dielectric layer 2450. In someembodiments, the backside dielectric layer 104 is a photoresist material(e.g., PBO) that has been coated, exposed, and developed to form theopenings 1340 as illustrated in FIG. 24. Because the sacrificialbackside dielectric layer 2450 has been cured, the sacrificial backsidedielectric layer 2450 remains during the patterning of the backsidedielectric layer 104. In some embodiments, the backside dielectric layer104 has a thickness of about 1 μm to about 10 μm, such as about 7 μm. Aswill be discussed in greater detail below, a through via willsubsequently be formed over the backside dielectric layer 104, whereinthe openings 1340 correspond to through via projections. A thickness ofabout 7 μm provides a sufficient thickness to shape the through viaprojections (e.g., tapered sidewalls) as well as providing a sufficientprocess window for an over etch process to expose portions of thesidewalls of the through via projections.

FIGS. 25-28 illustrate similar processes as those discussed above withreference to FIGS. 14-17, respectively, wherein like reference numeralsrefer to like elements, except the sacrificial backside dielectric layer2450 is present. After removing the carrier substrate 100 and therelease layer 102, the sacrificial backside dielectric layer 2450 may beremoved as illustrated in FIG. 29. In some embodiments, the sacrificialbackside dielectric layer 2450 is formed of a similar material as thebackside dielectric layer 104 and is removed in a manner similar to thebackside dielectric layer 104 as discussed above with reference to FIG.21. For example, the removal of the sacrificial backside dielectriclayer 2450 may be performed using a dry etch process using, for example,Ar, N₂, CF₄, O₂, or the like. The removal process may be controlled toover etch such that the backside dielectric layer 104 is recessed belowa surface of the through via projections 1442 such that portions ofsidewalls of the through via projections 1442 are exposed. In someembodiments, the backside dielectric layer 104 is recessed such that thethrough via projections 1442 protrude for a distance D2 equal to orgreater than about 2 μm. By recessing the backside dielectric layer 104and exposing sidewalls of the through vias projections 1442 by adistance such as D2, backside connectors 830 (e.g., solder) subsequentlyformed over the through vias projections 1442 may extend along thesidewalls of the through vias projections 1442 and/or the through vias206, increasing the contact surface area. In some embodiments, thisincreased contact surface between the solder and the through viasprojections 1442 and/or the through vias 206 may increase thereliability.

Thereafter, as illustrated in FIGS. 30 and 31, processes similar tothose discussed above with reference to FIGS. 19 and 20, respectively,may be performed to form the backside connectors 830, attach thestructure to other substrates (e.g., the first substrate 932 and/or thesecond substrate 934), and forming a molding underfill 936. In someembodiments, the molding underfill 936 may not extend along sidewalls ofthe second substrate 934. Though not shown, a molding underfill may alsobe formed between the first substrate 932 and passivation layer 524,surrounding the front-side connectors. As illustrated in FIG. 31, thebackside connectors 830 sit directly on and extend along sidewalls ofthe through via projections 1442 in some embodiments.

FIGS. 32-40 illustrate cross-sectional views of intermediate steps informing a semiconductor package in accordance with some embodiments. Asdiscussed above, the through vias 206 are exposed after the removal ofthe carrier substrate 100. In some embodiments, a backsideredistribution structure may be formed over the backside dielectriclayer 104 prior to forming the through vias 206. Accordingly, FIGS.32-40 illustrate an embodiment similar to that discussed above withreference to FIGS. 24-31 with a backside redistribution structure.

Referring first to FIG. 32, there is shown an embodiment similar to thatillustrated in FIG. 24, wherein like reference numerals refer to likeelements. Where the openings 1340 in the backside dielectric layer 104corresponds to the through via projections 1442 in FIG. 24, the openings1340 in the backside dielectric layer 104 in FIG. 32 corresponds to anoutermost backside redistribution layer. In some embodiments, thebackside dielectric layer 104 has a thickness of about 1 μm to about 10μm, such as about 7 μm. A thickness such as this provides a sufficientthickness for a conductive layer and process window to partially exposesidewalls of the backside dielectric layer 104 in a subsequent step.

FIG. 33 illustrates a backside redistribution structure 3160 including afirst backside metallization layer 3162 formed in a first backsidedielectric layer 3164 and a second backside dielectric layer 3166. Thebackside redistribution structure 3160 may be formed using similarprocesses and materials as those used to form the front-sideredistribution structure 518 as discussed above with reference to FIG.5.

FIGS. 34-40 illustrate similar processes as those discussed above withreference to FIGS. 25-31, respectively, wherein like reference numeralsrefer to like elements. After removing the carrier substrate 100 and therelease layer 102, the sacrificial backside dielectric layer 2450 may beremoved. In some embodiments, the sacrificial backside dielectric layer2450 is formed of a similar material as the first backside dielectriclayer 3164 and is removed in a manner similar to the backside dielectriclayer 104 as discussed above with reference to FIG. 29. For example, theremoval of the sacrificial backside dielectric layer 2450 may beperformed using a dry etch process using, for example, Ar, N₂, CF₄, O₂,or the like. The removal process may be controlled to over etch suchthat the first backside dielectric layer 3164 is recessed below asurface of the first backside metallization layer 3162 such that atleast a portion of the sidewalls of the first backside metallizationlayer 3162 are exposed.

In some embodiments, the first backside dielectric layer 3164 isrecessed by depth D3 of equal to or greater than 2 μm. By recessing thefirst backside dielectric layer 3164 and exposing sidewalls of the firstbackside metallization layer 3162 by a distance such as D2, backsideconnectors 830 (e.g., solder) subsequently formed over the firstbackside metallization layer 3162 may extend along the sidewalls of thefirst backside metallization layer 3162, increasing the contact surfacearea. In some embodiments, this increased contact surface between thesolder and the first backside metallization layer 3162 may increase thereliability.

Thereafter, as illustrated in FIGS. 39 and 40, processes similar tothose discussed above with reference to FIGS. 30 and 31, respectively,may be performed to form the backside connectors 830, attach thestructure to other substrates (e.g., the first substrate 932 and/or thesecond substrate 934), and forming a molding underfill 936. Asillustrated in FIG. 40, the backside connectors 830 sit directly on andextend along sidewalls of the first backside metallization layer 3162 insome embodiments.

FIGS. 39 and 40 also illustrates that one or more of the traces, such astrace 3970 may also be exposed. The trace 3970 represents a trace (e.g.,a trace running into and out of the page) formed in the first backsidemetallization layer 3162 and may connect to one or more of the backsideconnectors. As illustrated in FIG. 40, exposed portions of the trace3570 may be covered with molding underfill 936, protecting the trace3970 from the external environment. In some embodiments, the moldingunderfill 936 may not extend along sidewalls of the second substrate934. Though not shown, a molding underfill may also be formed betweenthe first substrate 932 and passivation layer 524, surrounding thefront-side connectors.

In some embodiments, a method of manufacturing a semiconductor device isprovided. The method includes forming a first layer over a carriersubstrate and forming a through via on the first layer. An integratedcircuit die is placed over the first layer, and a molding compound isformed over the first layer such that the molding compound extends alongsidewalls of the integrated circuit die and the through via. Afterremoving the carrier substrate, the first layer is completely removed.

In some embodiments, a method of manufacturing a semiconductor device isprovided. The method includes forming a first layer over a carriersubstrate, the first layer having an opening, and forming a through viaon the first layer, the through via extending into the opening. Anintegrated circuit die is placed over the first layer, and a moldingcompound is formed over the first layer, the molding compound extendingalong sidewalls of the integrated circuit die and the through via. Aredistribution layer is formed over the integrated circuit die and thethrough vias. After removing the carrier substrate, the first layer isexposed and recessed such that the through via protrudes from firstlayer.

In some embodiments, a semiconductor device is provided. Thesemiconductor device includes an integrated circuit die having afront-side and a backside. Molding compound is adjacent sidewalls of theintegrated circuit die. A first layer extends over the molding compound,the through via having a through via projection extending through thefirst layer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device comprising: an integratedcircuit die, the integrated circuit die having a front-side and abackside; molding compound adjacent sidewalls of the integrated circuitdie; a through-via extending through the molding compound; and a firstlayer extending over the molding compound, the through via having athrough via projection extending through the first layer.
 2. Thesemiconductor device of claim 1, wherein the through via projection hasa width less than a width of the through via extending through themolding compound.
 3. The semiconductor device of claim 2, wherein thethrough via projection protrudes from the first layer.
 4. Thesemiconductor device of claim 3, wherein the through via projectionprotrudes from the first layer by a distance equal to or greater than 2μm.
 5. The semiconductor device of claim 1, wherein sidewalls of thethrough via projection are tapered.
 6. The semiconductor device of claim1, further comprising a redistribution structure over a front-side ofthe integrated circuit die.
 7. The semiconductor device of claim 6,wherein the through via projection extends beyond the backside of theintegrated circuit die.
 8. A semiconductor device comprising: anintegrated circuit die; molding compound encapsulating the integratedcircuit die; a redistribution layer on a first side of the moldingcompound; a dielectric layer on a second side of the molding compoundopposite the first side; an electrical conductor disposed at leastpartially in the dielectric layer; and a solder region extending alongsidewalls of the electrical conductor, wherein the solder region iselectrically connected to the redistribution layer through theelectrical conductor.
 9. The semiconductor device of claim 8, whereinthe electrical conductor comprises multiple layers.
 10. Thesemiconductor device of claim 9, wherein the electrical conductorcomprises a first conductor and a second conductor, the first conductorextending through the molding compound, wherein a first surface of thefirst conductor is level with a surface of the molding compound, andwherein the second conductor contacts the first surface of the firstconductor.
 11. The semiconductor device of claim 8, wherein theelectrical conductor comprises a single continuous conductor extendingcompletely through the molding compound.
 12. The semiconductor device ofclaim 8, wherein the electrical conductor comprises a first portion inthe molding compound and a second portion in the dielectric layer, awidth of the first portion being greater than a width of the secondportion.
 13. The semiconductor device of claim 12, wherein sidewalls ofthe second portion are tapered.
 14. The semiconductor device of claim12, wherein an upper surface of the first portion is level with asurface of the molding compound.
 15. A semiconductor device comprising:a first package comprising: an integrated circuit die; molding compounddisposed around the integrated circuit die; and a through via extendingthrough the molding compound and extending above a top surface of themolding compound; and a second package over and bonded to the firstpackage by an electrical connector.
 16. The semiconductor device ofclaim 15, wherein a solder region of the electrical connector extendsalong a sidewall of the through via.
 17. The semiconductor device ofclaim 15, wherein sidewalls of the through via in the molding compoundare collinear with sidewalls of the through via extending above the topsurface of the molding compound.
 18. The semiconductor device of claim15, further comprising an insulating layer over the top surface of themolding compound, wherein the through via extends above a top surface ofthe insulating layer.
 19. The semiconductor device of claim 15, furthercomprising an underfill interposed between the first package and thesecond package.
 20. The semiconductor device of claim 15, wherein thethrough via has a ledge, a surface of the ledge being level with the topsurface of the molding compound.